Fiber reinforced plastic laminate construction of an airfoil wing type member

ABSTRACT

A laminate construction for an airfoil wing type member, such as a helicopter rotor blade, is produced by machine winding multiple layers of reinforcing fiber about a foil-like material support layer on a rotatable mandrel. The laminate construction is cut from the mandrel and shaped to the desired configuration in a mold cavity with the addition of a hardenable resin filler material. In adjacent layers the fibers are wound to form a diamond shaped pattern. The pitch angles of the fibers in different layers can be varied to accommodate different conditions, and, in addition, the length of the wound layers along the mandrel can be varied as required.

United States Patent 1 Brunsch 51 Jan. 30, 1973 [54] FIBER REINFORCEDPLASTIC LAMINATE CONSTRUCTION OF AN AIRFOIL WING TYPE MEMBER [75]Inventor: Klaus Brunsch,Weidach,Germany [73] Assignee:Messerschmitt-Bolkow-Blohm Gesellschalt mit beschraenkter Haf- [30]Foreign Application Priority Data Aug. 10, 1969 Germany ..P 17 79 433.1

FOREIGN PATENTS OR APPLICATIONS 831,380 3/1960 Great Britain ..416/230412,300 6/1934 Great Britain ..416/229 Primary Examiner-Everette A.Powell, Jr. A!t0mey-McGlew and Toren ABSTRACT A laminate constructionfor an airfoil wing type member, such as a helicopter rotor blade, isproduced by machine winding multiple layers of reinforcing fiber about afoil-like material support layer on a [52] ....4l6/226, 416/230, 416/241rotatable mandrel. The laminate construction is cut [51] Int. Cl ..B64c11/26 from the mandrel and shaped to the desired configura- [58] Fieldof Search ..416/229, 241 230, 226 tion in a mold cavity with theaddition of a hardenable resin filler material. ln adjacent layers thefibers are [56] References Cited wound to form a diamond shaped pattern.The pitch angles of the fibers in different layers can be varied toUNITED STATES PATENTS accommodate different conditions, and, inaddition, 2,202,013 5/1940 Lougheed ..416/230 UX the length of the woundlayers along the mandrel can 2,380,336 7/1945 Schwebel ..416/229 UX bevaried as required, 2,414,125 1/1947 Rheinfrank ..416/230 UX 3,237,6973/1966 Ford et al. ..416/230 UX 2,175,204 10/1939 2 202 014 5,194 4Claims, 9 DIflWlllg Figures 2,995,777 8/1961 Warnken ..18/36 k I QHutter et al. ..156/196 PATENTEDJANBO ms 4 3.713.753

sum 1 or 2 INVENTOR Klaus Brunsch Wwa-l7m ATTORNEYS PAIENTEnmao 197sSHEET 2 BF 2 iiiiiiiimlllllllllllllllun Fig. 8

INVENTOR w mm am 2 FIBER REINFORCED PLASTIC LAMINATE CONSTRUCTION OF ANAIRFOIL WING TYPE MEMBER The invention is directed to the structure ofan airfoil wing type member, such as a rotor blade for a helicopter,and, more particularly, it is directed to a laminate structure used informing such a member and also to the method of and apparatus forforming such a structure. The laminate structure is formed of machinewound fibers set in a hardenable resin filler material. In addition, theinvention concerns the construction of the airfoil wing type member andof component parts for securing the member to a support.

In the past, in the production of laminate structures for airfoil wingtype members and the like, the cover layers have been laminated intomold cavities by hand using the contact method. Next, reinforcementcords, such as spar supports or the like, were built up and laminated byhand from single rovings using wet-in-wet bonding in the mold cavity. Inthis operation, the desired shape was attained by using a spatula andfollowing a template. Only trained teams of specialists have been ableto do this work satisfactorily, as experience has shown, and anyunexpected absence of a member of such a team results in delays in theprogress of the work. However, even with expert cooperation from all ofthe team members, deviations in weight or other conditions of thestructure are inevitable in the production of a number of similarlydimensioned structures of this kind. As can be readily appreciated, thedifferences in work performed by hand are unavoidable, such as arecaused by external influences or uncontrollable conditions. Moreover,the time required for the production of such fiber-reinforced plasticstructures is generally quite long, in particular for the stepsinvolving filling the mold. Accordingly, since it takes considerabletime to build up the reinforcement cores or spars from individualrovings, the expensive pressing mold, in which the laminate structuresare formed is taken out of use. These various characteristics of handmade laminate structures are obstacles to economical production andespecially to quantity production. By means of the present invention, itis possible to avoid the variations in production which result from handwork and it is also possible to reduce, to a considerable extent, thetime spent in forming the laminate structure and producing the airfoilwing type member. At the same time, while maintaining the quality of theproducts produced at a constant level, it is also possible to handle wetlaminates formed outside the mold and which consist, at least in part,of large-area resin impregnated fabrics or webbing.

A primary object of the invention is the formation of a fabric orwebbing composed of multiple layers of fibers, which form, in part, theshell and inserts for the laminate structure. The fibers are machinewound or coiled on a mandrel or core and are used in forming thedifferent parts of the laminate structure. In this portion of theprocess, which is known in itself, the fibers or filaments are woundabout a separator layer formed of a foil-like material wrapped about arotatable mandrel. The fibers are guided as they are wound onto themandrel and the pitch angle of the fibers can be varied depending on thedirection of the stress to be experienced in the member formed from thelaminate structure.

After completing the winding of the fibers on the mandrel, the laminatestructure formed is removed and inserted into a press mold cavity inwhich the separator layer acts as a support and additional hardenableresin filler material is applied, in either a wet or prehardened state,and then the laminate structure is pressed in a known manner to completethe hardening or curing operation. In removing the laminate structure ofthe separator layer and the wound fibers from the mandrel it it cutalong a line parallel with the axis of the mandrel and is lifted off inone or more sections. The sections removed from the mandrel are thenused as the cover or shell of an airfoil wing type member to be formed.The size ratio between the laminate structure formed and the windingmandrel is of secondary importance. Depending on the parameters of themember to be formed in the mold, one or more sections can be cut fromthe structure wound on the mandrel, and, if necessary, subsequently theycan be cut to shape.

At the present time an airfoil or driving wing formed offiber-reinforced plastic shells has been known where the supportingshell is constructed from a plurality of cords embedded in plastic andarranged in side by side relationship extending in the longitudinaldirection of the wing. Such a structure built in the conventional mannerin a pressing mold is disclosed in German Auslegeschrift No. 1,045,810.The disadvantage of such a construction have been described above.

By means of the present invention, it is possible to produce a number ofidentical machine wound component parts for a series of structures. Withthe formation of the webbing or fabric by automatic means thefluctuating conditions previously experienced are avoided and thecomponent parts can be formed with great precision.

With the present invention, it is possible to dispense with the need forexpensive specialized labor and to effect a major reduction in theproduction times required for the formation of the laminate structure.In addition, it is possible to prefabricate various sections of themember to be produced in advance of the time for the final constructionand the laminate structures can be stored in a semi-hardened state for ashort period of time or in a pre-hardened state for a prolonged period.By virtue of the separator layer of the foil-like material proposed bythe present invention, which acts as a support for the fibers wound onthe mandrel, the separator layer permits easy removal of the woundcomponent from the mandrel and it also makes it possible to handle andtransport wet webbing formed of the wound fibers which are otherwisesensitive to mechanical stress. In addition, the separator layer servesto assist in sucking or pressing the fiber structure against the wall ofthe mold cavity as well as against other parts of the finishedstructure, for example, against a supporting core made of hard foammaterial.

Other important advantages of the invention stem from the machinewinding of the fibers or filaments on the separator layer covering themandrel which permits variations in the pitch angle of the fibers toaccommodate the varying conditions in the member being formed. Forexample, in a rotor blade, in addition to being subject to centrifugalloads, it is also exposed to torsion stresses which are absorbed mainlyin the shell or cover of the blade and also to bending loads which areabsorbed in the spar or longitudinal support structure of the rotorblade. These various stresses are not the same in all of thecross-sectional planes of the rotor blade but vary in dependence on theblade suspension and also in accordance with the dimensions of the bladeat a particular point. Since, in accordance with the present invention,it is possible to orient the fibers in the laminate structure in aselected arrangement, these various-stresses can be accommodated bypurposefully arranging the pitch angle of the fibers as they are wound.Another advantage gained in the present invention is applicable when thelaminate structure is used in forming the spar for the rotor blade sincethe fiber reinforcement is seamless the main load extendingsubstantially in the direction of the fibers cannot impinge on a seamarea of low rupture limit.

Another feature of the present invention is the manner in which theseparator layer formed of a foillike material can be employed as a partof the shell of the finished airfoil type member or can be removed inthe process of forming the member. After the fibers are wound on theseparator layer and the thus formed laminate structure is cut andremoved from the mandrel, it is placed within the cavity of a pressingmold and by vacuum means the structure is secured firmly within thecavity as the member hardens. In this manner, the separator layer formsan outer protective layer for the member and remains as a part of thecover layer or shell of the member. Alternatively, the separator layermay be removed from the laminated fiber webbing after the webbing hasbeen securely placed in the mold cavity with the separator layer facingthe mold separation plane.

In either of the above methods undesired air pockets are eliminated frombetween the mold cavity wall and the laminate structure and thefoil-like material separator layer serves as a support for the fiberlayers to assure that it is applied in a uniform manner against the moldcavity wall.

In forming the shell for the airfoil wing type member or its spar thewinding of the fibers is performed in accordance with known filamentwinding methods with the same or different winding or pitch angles inthe different layers. In certain cases it is advantageous to perform thewinding with different types of filaments or fibers in different layers,for example,.glass, metal or other fibers, for accommodating the variousconditions to be experienced within the member. In addition, when usingdifferent types of fibers, different pitch angles may be used for eachof the particular fiber types employed. Moreover, the different pitchangles employed may be used over the entire length of the mandrel oronly over a selected part of its length in dependence on the conditionsto be experienced within the member being formed.

Preferably, the parts of the airfoil wing type member to be formed whichare closest to its axis of rotation are produced first. For example, byestablishing a provisional turning point on the mandrel the winding canbe performed first along a part of the mandrel length and then thewound'fiber can be severed, for example, by means of a cutting wheel. Bysubsequently shifting the turning point laterally along the length ofthe mandrel one part of the coil length can be enlarged in relationshipto the remainder of the wound structure to provide a step-wise wallthickness which can be varied in accordance with the stress peaks to beexperienced in the member being formed.

In winding the laminate structure, especially for the formation of thespar for the member, by introducing a suitable fluid medium, eitherliquid or gaseous, such as compressed air, through the circumferentialperiphery of the mandrel into the space between its outer surface andthe separator layer formed of the foil-like material, the laminatestructure can be expanded and its removal from the mandrel facilitated.This arrangement is of particular advantage for long coil bodies havinga relatively small diameter. The slight expansion of the laminatestructure due to the introduction of the pressurized fluid medium can betaken into account in establishing the winding angle, that is, thewinding angle can be made smaller than the pitch angle for the fullyhardened and expanded structure.

Another feature of the invention involves filling the hollow spar orlongitudinal support for the finished member with a heated pressurizedfluid medium to expand the spar and to press the laminate structureagainst the enclosing parts of the air foil wing type member. To effectthis interior pressurization of the spar a device is employed whichcomprises a hollow mandrel with nozzle type openings through itsperiphery through which a fluid medium can be forced between the mandrelsurface and the separator layer of foil-like material. With thisarrangement,considerable difficulties which have been experienced in thepast can be avoided and the wound fibers and plastic materials can beembedded into the shell forming the outer layer of the member. Theoutward pressurization of the spar structure is matched by the closingpressure of the mold.

In addition, the present invention involves the formation of a junctionmember of a similar hardened laminate structure to provide theattachment of the airfoil wing type member to a support. The junctionmember is wound as a hemisphere at one end with a transition sectionsecuring it to a support. The hemisphere is formed with an aperture inits domed shaped construction and the aperture is defined by atoroidally thickened edge or rim for receiving an anchoring member whichcan be formed of metal. By this arrangement the time consuming chore ofplacing loop type attachment members, consisting of rovings, as used inthe past, can be eliminated. In addition, in attaching the member to itssupport a support ring is used in' securing an anchor member to thejunction member.

Another element of the invention is the machine employed for winding thefibers, such as plastic coated fibers on a revolving mandrel. Themachine is formed by a winding head which is moved back and forth alonga mandrel in a line parallel with its axis of rotation. The machine isprovided with a device for varying the speed of travel of the windinghead and also of the rotation of the mandrel so that the pitch angle ofthe fibers or filaments wound can be varied, preferably within limitsbetween 0 and 45. By means of this device, it is possible, such as inthe formation of the spar, to dispose the reinforcement fibers atdifferent pitch angles along the total length of the spar in accordancewith the stresses to be experienced during the operation of the airfoilwing type member.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated and described preferredembodiments of the invention.

In the Drawings:

FIG. 1 shows, in a perspective view, the manner of winding a laminatestructure for use in forming an airfoil wing type member;

FIG. 2 is a side view of a mold cavity with a laminate structure placedin the cavity;

FIG. 3 is a mold cavity similar to that in FIG. 2, but with the laminatestructure in a reversed position;

FIG. 4 is a longitudinal sectional view of a core or mandrel for use informing a spar member;

FIG. 5 is a sectional view of an airfoil wing type member illustratingthe blade root and its junction member;

FIG. 6 is a transverse sectional view taken along line VI-Vl in FIG. 5;

FIG. 7 is a transverse sectional view taken along line VII-VII in FIG.5;

FIG. 8 is a transverse sectional view through an airfoil wing typemember incorporating the spar illustrated in FIG. 7; and

FIG. 9 is a somewhat schematic plan view on a reduced scale, of afinished airfoil member.

In FIG. I a rotating mandrel l is shown having a separator layer of afoil-like material covering the circumferential periphery of themandrel. On the outer surface of the foil-like material 2, fibers orfilament like members 3 are machine wound back and forth along themandrel so that adjacent layers of the multi-layer webbing formed on theseparator layer are disposed in a diamond shaped winding pattern.Accordingly, a laminate structure 4 of a multiple number of layers ofmachine wound fibers is provided on the base or separator layer 2. Whenthe laminate structure 4 is completely wound, one or a number ofsevering cuts extending in the axial direction a of the mandrel are madefor removing the structure in one or a number of mats or sheets whichare placed in the mold cavity 5 (see FIGS. 2 and 3).

Each of FIGS. 2 and 3 shows one-half of a mold, the mirror-symmetricalother halves of the molds are not shown. The top edge b of the mold halfas shown affords the division plane between the two mold halves. Inremoving the laminate structure from the mandrel the separator layer 2serves as a support. In FIG. 2, the foil-like material 2 is facedoutwardly and the laminate structure 4 formed of the wound fibers ispositioned against the surface of the cavity 5. The laminate structureis applied in a positive manner against the surface of the cavity eitherby a pressure device not shown, which may be operated hydraulically orpneumatically, or by vacuum means which operate in the manner indicatedby the arrows c and the passageways extending through the mold to thesurface of its cavity. When a suction effect is employed, it actsthrough the porous and gas permeable laminate structure and pulls theseparator layer 2 firmly against the mold cavity surface.

Due to the vacuum effect any air inclusions within the laminatestructure are eliminated.

As indicated in FIG. 3, when a vacuum effect is being employed, apacking 6 must be inserted in the edge zone of the mold cavity 5 so thata seal is provided between the laminate structure 4 and its separatorlayer 2 and the surface of the mold cavity. In FIG. 3, the positions ofthe separator layer 2 and the fiber laminate structure 4 are reversed sothat the separator layer is disposed against the surface of the moldcavity. This arrangement of the separator layer-laminate structureshould be employed when the foil-like material of the separator layer isto serve as the outer protective surface or shell of an airfoil wingtype member, such as a rotor blade, after the molded member has beensufficiently hardened.

FIG. 4 shows the arrangement of a winding mandrel for making a spar fora rotor blade. The mandrel is formed of a hollow closed metallic casing7 having a connecting pipe 8 through which a fluid medium having aninternal pressure P can be supplied into the man-v drel. In thegenerated or lateral peripheral surface 9 of the mandrel a number ofspaced bores 10 are provided through which the pressurized fluid mediumis introduced between the surface 9 and the separator layer 21. Aplurality of stepped wound fiber course l3, l4 and 15 are provided onthe separator layer 21. On the exterior surface of the mandrelprovisional turning flanges 11 and 12 are provided so that the course 15of wound fibers extends for the entire wound length fof the spar whilethe other fiber courses l3 and 14 extend for the lengths d, e,respectively, which represent only a portion of the entire length of thespar. As can be noted the fiber course 15 forms the exterior surface ofthe laminate structure extending over both of the other courses l3 and14 while the course 14 extends over the inner course 13. The steppedoffsets resulting from the shorter course lengths d and e are roundeddue to the overlying courses which are longer in the axial direction ofthe mandrel. As indicated in FIG. 4, each of the courses has a differentpitch angle, for example, course 13 having the length d has a pitchangle of 45 while the course 14 having a length e has a pitch angle of30 and course 15 with the full length f of the spar has a pitch angle of15. Accordingly, the thickness of the wound laminate structure can beadapted to the particular load characteristics affecting the spar duringoperation and this accommodation is achieved in a simple manner.

Depending on the stresses or loads which act on the spar it is possibleto employ fibers of different materials, such as glass, metal or othertypes, for the different courses 13, 14 and 15 of the laminatestructure. The use of fibers of different types can be easilyaccommodated in the winding method employed in the present invention.

In FIG. 5, a junction member 16 is shown for securing the rotor blade toits support. The junction member 16 is formed in the same manner as thebody of the rotor blade. In forming the junction member a mandrel, notshown, is used with the fibers being placed on the end of the mandrel bythe known polar winding method. As constructed, the junction member hasa hemispherical end section 16a of enlarged cross section which narrowsdown in a transition section 16b to the cross sectional dimensions ofthe spar S. The end section 16a has an opening 25 defined by a toroidaledge 17 of the fiber wound member. A metallic anchoring member 18 issecured within the hemispherical shaped end of the junction member 16and the anchoring member is connected to the rotor head, not shown, by asupport 19. Positioned on the toroidal edge 17 of the junction member 16is a retention ring 20 which is fixed to the anchoring member 18 andcontacts the end sec tion 16a about its toroidal edge 17.

In FIGS. 6 and 7, transverse sections of the junction member 16 and thespar S are indicated. By comparing the sections shown in FIGS. 6 and 7it will be apparent that the transition section 16b of the junctionmember 16 changes from the oval shape shown in FIG. 7 to the circularshape indicated in FIG. 6. In the cross section of the spar theseparator layer of foil-like material 21 is used as a pressure tubingfor applying the fiber laminate structure 13-15 against the laminatestructure forming the outer shell of the rotor blade. The separatorlayer 21 remains in the interior of the blade after the synthetic resinsincorporated with the fibers have hardened.

In FIG. 8, a transverse section of the completed rotor blade is shownwith the combined separator layer 2 and laminate construction 4 formingthe hardened shell of the blade which encloses the spar S formed by thewound courses 13, 14 and on the separator layer 21. Additionally, asupporting-body 22 formed of a hard foam material is placed within therotor blade shell and contacts a portionof the exterior of the spar.Further, other parts not shown, can be incorporated into the blade suchas weights for correcting the position of axis of gravity of the blade.Along the leading edge of the airfoil wing type member, the edges 23 ofthe separator layer projecting beyond the mold edge are trimmed offafter the rotor blade has hardened.

In FIG. 9, a finished rotor blade 24 is shown having a junction member16, as illustrated in detail in FIG. 5, secured by means of a retentionring to an anchoring member 18 which, in turn, is secured within asupport 19. From the schematic representation of the formation of thefiber wound laminate structure of the rotor blade it can be seen thatthe fibers underlying the separator layer 2 have different pitch anglesat spaced locations from the junction member 16.

As layer 2 a thin sheet of 0.01 in. of polyethylene or polyvinylchloridecan be used. The junction member 16 according to FIG. 5 is suitably madeby coiling machines as known, for example, from the publication"FILAMENT WINDING, by Rosato Grove, 1964 Interscience Publishes, Wiely &Sons, New York. It is also possible to coil such junction members 16 byhand.

I claim:

1. A laminate structure for forming the shell of an airfoil wing typemember comprising a support layer formed of a foil-like material, aresin impregnated webbing formed on said support layer, said webbingcomprising a, plurality of superposed layers of machine wound fibers,said fibers in each said layer having the 1 same winding angle anddisposed in laterally spaced relationship to one another, in adjacentsaid layers in which said fibers have the same winding angle the windingangle is reversed for forming a diamond shaped windin pattern by meansof the adjacent layers, and sar webbing having at least two groups ofsaid layers with the layers in each said group having a winding anglewhich is different from the winding angle of the other said group.

2. An airfoil wing type member comprising a longitudinally extendingtubular shaped spar support having an oval shaped transverse section andcomprising an inner layer formed of a foil-like material and an outerlayer of resin impregnated fibers machine wound in a laterally spacedmanner into a multiplicity of superposed layers with the fibers disposedat a pitch angle arranged obliquely to longitudinal axis of saidsupport, said layers arranged in a number of superposed groups with saidlayers in each group having the same winding angle which is differentfrom the winding angle of the other groups, adjacent said layers in eachof said groups having the direction of the winding angle reversed forproviding a diamond shaped winding pattern by means of the adjacentlayers, a junction membervintegrally secured to one end of said sparsupport and comprising a transition section extending axially from saidspar support and terminating in a hemispherically shaped section locatedat the endof said transition section remote from said support, saidtransition section having an oval shaped cross section at its connectionto said support and the cross section being changed to a circular one atits end integrally secured to said hemispherically shaped section, saidjunction member comprising a hardened laminate structure comprising aninner foillike layer and a multiplicity of machine wound fibers aboutsaid foil-like layer for the length of said transition andhemispherically shaped sections, said hemispherically shaped sectionhaving an aperture centrally arranged therein and said fibers beingwound in said hemispherically shaped section to provide a toroidallyshaped thickened edge defining the periphery of the aperturetherethrough.

3. An airfoil wing type member, as set forth in claim 2, comprising ananchor member inserted into said hemispherically shaped section of saidjunction member through the aperture-therein, a support ring disposedabout said anchor member exteriorly of said junction member and securingsaid anchor member-to said junction member.

4. An airfoil wing type member, as setforth in claim 2, wherein a shellis formed on said support spar with said shell having an airfoil shapedand comprising an upper section and a lower section joined togetheralong a longitudinally extending seam. at the leading edge and trailingedge of the airfoil shape, each of said upper and lower sectionscomprising an outer layer of a foil-like material and a multiplicity oflayers of resin impregnated machine wound fibers disposed on the innersurface of said foil-like layer,'and a filler material being positionedbetween said upper and lower sections exteriorly of said spar supportfor completely filling the space between said upper and lower sections.

i i 11! k

1. A laminate structure for forming the shell of an airfoil wing typemember comprising a support layer formed of a foil-like material, aresin impregnated webbing formed on said support layer, said webbingcomprising a plurality of superposed layers of machine wound fibers,said fibers in each said layer having the same winding angle anddisposed in laterally spaced relationship to one another, in adjacentsaid layers in which said fibers have the same winding angle the windingangle is reversed for forming a diamond shaped winding pattern by meansof the adjacent layers, and said webbing having at least two groups ofsaid layers with the layers in each said group having a winding anglewhich is different from the winding angle of the other said group.
 1. Alaminate structure for forming the shell of an airfoil wing type membercomprising a support layer formed of a foil-like material, a resinimpregnated webbing formed on said support layer, said webbingcomprising a plurality of superposed layers of machine wound fibers,said fibers in each said layer having the same winding angle anddisposed in laterally spaced relationship to one another, in adjacentsaid layers in which said fibers have the same winding angle the windingangle is reversed for forming a diamond shaped winding pattern by meansof the adjacent layers, and said webbing having at least two groups ofsaid layers with the layers in each said group having a winding anglewhich is different from the winding angle of the other said group.
 2. Anairfoil wing type member comprising a longitudinally extending tubularshaped spar support having an oval shaped transverse section andcomprising an inner layer formed of a foil-like material and an outerlayer of resin impregnated fibers machine wound in a laterally spacedmanner into a multiplicity of superposed layers with the fibers disposedat a pitch angle arranged obliquely to longitudinal axis of saidsupport, said layers arranged in a number of superposed groups with saidlayers in each group having the same winding angle which is differentfrom the winding angle of the other groups, adjacent said layers in eachof said groups having the direction of the winding angle reversed forproviding a diamond shaped winding pattern by means of the adjacentlayers, a junction member integrally secured to one end of said sparsupport and comprising a transition section extending axially from saidspar support and terminating in a hemispherically shaped section locatedat the end of said transition section remote from said support, saidtransition section having an oval shaped cross section at its connectionto said support and the cross section being changed to a circular one atits end integrally secured to said hemispherically shaped section, saidjunction member comprising a hardened laminate structure comprising aninner foil-like layer and a multiplicity of machine wound fibers aboutsaid foil-like layer for the length of said transition andhemispherically shaped sections, said hemispherically shaped sectionhaving an aperture centrally arranged therein and said fibers beingwound in said hemispherically shaped section to provide a toroidallyshaped thickened edge defining the periphery of the aperturetherethrough.
 3. An airfoil wing type member, as set forth in claim 2,comprising an anchor member inserted into said hemispherically shapedsection of said junction member through the aperture therein, a supportring disposed about said anchor member exteriorly of said junctionmember and securing said anchor member to said junction member.